Co and S Dual-Doped Carbon Derived from Endogenous Sulfurcontaining 2-Thiobarbituric Acid: Application in PMS Activation for Ultra-rapid Degradation of Norfloxacin

Abstract

Heteroatom doping represents an effective strategy for enhancing catalytic performance. Cobalt-sulfur/carbon catalyst (denoted as Co 9 S 8 /C) were synthesized via high-temperature calcination using a endogenous sulfur-containing precursors, namely 2-thiobarbituric acid. The as-prepared Co 9 S 8 /C was employed as a heterogeneous catalyst to activate peroxymonosulfate (PMS) for the degradation of norfloxacin (NOR). Interestingly, under the optimized conditions of 0.05 g/L Co 9 S 8 /C, 0.3 g/L PMS, and pH = 7, the degradation efficiency of NOR (50 mg/L, 50 mL) was achieved 84.0 % and 93.6 % in 3 and 15 min, respectively. The NOR removal efficiency still retained 73.8 % after 5 cycles. Radical scavenging experiments showed that the NOR degradation mechanism involved coordinating of sulfate radicals (SO 4 • -), hydroxyl radicals ( • OH), superoxide radical (O 2 • -), and singlet oxygen ( 1 O 2 ) playing a more significant role. However, 1 O 2 was demonstrated to dominate in the efficient removal of NOR. The result from electron paramagnetic resonance (EPR) experiment evidenced that Co 9 S 8 /C triggered rapid PMS activation in 3 min. This study offered a fresh idea of the PMS highly effective activator preparation method to encourage the effective and practical application of the rapid degradation of organic pollutants.